Internal combustion engines, such as automobile and other vehicle engines, operate at relatively high temperatures due generally to the internal combustion and the friction of the moving parts. If the engine temperature gets too hot, the engine may malfunction, or worse, the moving metal parts of the engine may seize up and ruin the engine. Accordingly, most vehicle internal combustion engines are coupled to a cooling system which maintains the temperature within a preferred operating range to insure proper functioning of the engine and reduced wear.
One type of commonly used cooling system is a closed loop liquid cooling system. In a closed loop system, a cooling liquid such as water or antifreeze or a mixture of both, is circulated through the engine to cool it. To this end, the engine has several passages formed therein through which the cooling liquid is circulated. The cooling liquid absorbs the engine heat and is circulated to another part of the system to dissipate that heat. The recirculated cooling liquid is constantly heated and cooled to cool the engine as it operates.
In a typical vehicle, the cooling system includes a water pump connected in the loop of the cooling system to drive the cooling liquid through the engine. A thermostat valve which is mounted proximate the engine controls the flow of the liquid. The thermostat valve opens when the vehicle engine reaches a particular temperature so that the liquid may circulate through the closed loop system and cool the engine. However, a cold engine does not function properly either, and therefore, a normally operating thermostat will remain closed and prevent circulation of the cooling liquid until the engine heats up to a desirable temperature range, and will then subsequently open to allow circulation of the cooling liquid.
The liquid passes out of the engine, through the thermostat, and through a hose which connects the thermostat to a heat exchange unit commonly referred to as a radiator. The radiator is metal and has a plurality of fins which absorb the heat from the heated liquid. Through air convection the fins dissipate the heat absorbed by the radiator. By passing through the radiator, the hot fluid from the engine is cooled and passes through an output hose back to the engine to again be heated while cooling the hot engine. As the engine runs and the vehicle moves, the cooling fluid is continuously circulated and recirculated through the closed loop cooling system to keep the engine running properly. A fan might be used proximate the radiator to supply a convective stream of air when the vehicle is not moving.
Additional heat exchangers also cool the engine within a closed loop cooling system. For example, a heater core located proximate the inside dashboard of the vehicle receives heated liquid from the engine and circulates the heated liquid around the core. The heater core absorbs heat from the liquid and heats up itself. The heat transferred from the cooling liquid to the heater core cools the liquid. The heated heater core then provides heat to the inside of the vehicle when necessary. The cooling liquid delivered to the heater core comes directly from the engine, and therefore, the temperature of that cooling liquid is a good indicator of the internal engine temperature.
Accordingly, to keep the vehicle engine running properly, the cooling system must also operate properly. Presently, checking a cooling system for proper operation is time consuming and oftentimes inaccurate as well as inefficient. After the engine is started and sufficiently warm, the radiator and thermostat must be individually checked, and the mechanic or owner of the vehicle has to monitor the temperature to make sure that the engine does not overheat. If one of the parts of the cooling system is marginal, the test has to be repeated to insure proper operation. Further, if repairs are made, the cooling system check would have to again be repeated. 0n average, the check takes from 20 to 30 minutes each time. Furthermore, cooling system repairs take anywhere from 20 minutes to one hour.
In the past, during repair and testing, the mechanic traditionally has had to pay close attention to the vehicle to avoid possible damage to the engine from overheating. Additionally, the engine and cooling system had to be watched for events such as the opening of the thermostat. A knowledgeable mechanic will feel the radiator hoses as the vehicle warms up in order to check temperature and pressure. However, a mechanic, while sometimes being able to determine the operational status of the thermostat and radiator, will not be able to do so in marginal cases.
Properly checking and repairing a cooling system in order to insure that it is operable requires a certain amount of expertise and experience. Even with such expertise, there is uncertainty involved regarding individual components, and even a skilled mechanic may miss marginal cases of component malfunction or failure. Furthermore, with the currently available cooling systems testing and repair procedures, it is often easier to replace a thermostat without regard for its condition than it is to check and make sure that the thermostat is functioning properly. This creates unnecessary expense to the vehicle owner because a mechanic may replace a perfectly good thermostat with a new thermostat. An additional expense during repair work and part replacement is the cost of replacing the coolant or anti-freeze liquid. During repairs, the entire coolant system often has to be drained and then subsequently refilled with new fluid which cumulatively becomes expensive.
Consequently, there is a need for a faster, simpler, more direct way of testing a cooling system in order to determine that it is functioning properly. There is further need for a way for a vehicle owner, who is generally a non-mechanic, to test the cooling system of his vehicle as effectively as a mechanic. Still further, there is a need for a way to quickly and effectively monitor the cooling system so that no time is wasted testing or actually replacing those parts which are operating satisfactorily. Additionally, it is desirable to reduce the amount of time spent on testing partially bad parts which are normally found by the process of elimination. In the past several bad parts in a system generally has required the mechanic or operator to test everything, one at a time. It is further desirable to be able to test and analyze a cooling system without having such testing subject to temperature disturbances outside the closed loop cooling system or other temperature transients outside of the engine.